﻿Shader "UI/ImageGrey"
{
	Properties
	{
		[PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
		_Color("Tint", Color) = (1,1,1,1)

		//MASK SUPPORT ADD
		_StencilComp("Stencil Comparison", Float) = 8
		_Stencil("Stencil ID", Float) = 0
		_StencilOp("Stencil Operation", Float) = 0
		_StencilWriteMask("Stencil Write Mask", Float) = 255
		_StencilReadMask("Stencil Read Mask", Float) = 255
		_ColorMask("Color Mask", Float) = 15
		//MASK SUPPORT END
	}

	SubShader
	{
		Tags
		 {
			"Queue" = "Transparent"
			"IgnoreProjector" = "True"
			"RenderType" = "Transparent"
			"PreviewType" = "Plane"
			"CanUseSpriteAtlas" = "True"
		 }

		//MASK SUPPORT ADD
		Stencil
		{
			Ref[_Stencil]
			Comp[_StencilComp]
			Pass[_StencilOp]
			ReadMask[_StencilReadMask]
			WriteMask[_StencilWriteMask]
		}
		ColorMask[_ColorMask]
		//MASK SUPPORT END

		// 源rgba*源a + 背景rgba*(1-源A值)   
		Blend SrcAlpha OneMinusSrcAlpha
		Pass
		{
			CGPROGRAM
				#pragma vertex vert     
				#pragma fragment frag     
				#include "UnityCG.cginc"     
			struct appdata_t
			{
				float4 vertex   : POSITION;
				float4 color    : COLOR;
				float2 texcoord : TEXCOORD0;
			};

			struct v2f
			{
				float4 vertex   : SV_POSITION;
				fixed4 color : COLOR;
				half2 texcoord  : TEXCOORD0;
			};

			sampler2D _MainTex;
			fixed4 _Color;

			v2f vert(appdata_t IN)
			{
				v2f OUT;
				OUT.vertex = UnityObjectToClipPos(IN.vertex);
				OUT.texcoord = IN.texcoord;
		#ifdef	UNITY_HALF_TEXEL_OFFSET     
				OUT.vertex.xy -= (_ScreenParams.zw - 1.0);
		#endif  
				OUT.color = IN.color * _Color;
				return OUT;
			}

			fixed4 frag(v2f IN) : SV_Target
			{
				half4 color = tex2D(_MainTex, IN.texcoord) * IN.color;
				float grey = dot(color.rgb, fixed3(0.22, 0.707, 0.071));
				return half4(grey,grey,grey,color.a);
			}
			ENDCG
		}
	}
}